The heartbeat of the volcano: The discovery of episodic activity at Prometheus on Io     

Ashley Gerard Davies  Lionel Wilson  Giovanni Leone  Windy Jaeger 《Icarus》2006,184(2):460-477

The temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface. The Galileo Near Infrared Mapping Spectrometer (NIMS) observed the volcano Prometheus, on the jovian moon Io, on multiple occasions between 1996 and 2002. The 5 micron (μm) brightness of this volcano shows considerable variation from orbit to orbit. Prometheus exhibits increases in thermal emission that indicate episodic (though non-periodic) effusive activity in a manner akin to the current Pu'u 'O'o-Kupaianaha (afterwards referred to as the Pu'u 'O'o) eruption of Kilauea, Hawai'i. The volume of material erupted during one Prometheus eruption episode (defined as the interval from minimum thermal emission to peak and back to minimum) from 6 November 1996 to 7 May 1997 is estimated to be ∼0.8 km³, with a peak instantaneous volumetric flux (effusion rate) of ∼140 m³ s⁻¹, and an averaged volumetric flux (eruption rate) of ∼49 m³ s⁻¹. These quantities are used to model subsurface structure, magma storage and magma supply mechanisms, and likely magma chamber depth. Prometheus appears to be supplied by magma from a relatively shallow magma chamber, with a roof at a minimum depth of ∼2-3 km and a maximum depth of ∼14 km. This is a much shallower depth range than sources of supply proposed for explosive, possibly ultramafic, eruptions at Pillan and Tvashtar. As Prometheus-type effusive activity is widespread on Io, shallow magma chambers containing magma of basaltic or near-basaltic composition and density may be common. This analysis strengthens the analogy between Prometheus and Pu'u 'O'o, at least in terms of eruption style. Even though the style of eruption appears to be similar (effusive emplacement of thin, insulated, compound pahoehoe flows) the scale of activity at Prometheus greatly exceeds current activity at Pu'u 'O'o in terms of volume erupted, area covered, and magma flux. Whereas the estimated magma chamber at Prometheus dwarfs the Pu'u 'O'o magma chamber, it fits within expectations if the Pu'u 'O'o chamber were scaled for the greater volumetric flux and lower gravity of Io. Recent volumetric eruption rates derived from Galileo data for Prometheus were considerably smaller than the rate that produced the extensive flows formed in the ∼17 years between the Voyager and Galileo missions. These smaller eruption rates, coupled with the fact that flows are not expanding laterally, may mean that the immediate heat source that generates the Prometheus plume is simultaneously running out of available volatiles and the thermal energy that drives mobilization of volatiles. This raises the question of whether the current Prometheus eruption is in its last throes.  相似文献   

Voronoi Meshing to Accurately Capture Geological Structure in Subsurface Simulations     

LaForce  Tara  Ebeida  Mohamed  Jordan  Spencer  Miller  Terry A.  Stauffer  Philip H.  Park  Heeho  Leone  Rosie  Hammond  Glenn 《Mathematical Geosciences》2023,55(2):129-161

Mathematical Geosciences - Mesh generation lies at the interface of geological modeling and reservoir simulation. Highly skewed or very small grid cells may be necessary to accurately capture the...  相似文献   

PAOLO: A Polarimeter Add‐On for the LRS Optics at a Nasmyth focus of the TNG     

S. Covino  E. Molinari  P. Bruno  M. Cecconi  P. Conconi  P. D'Avanzo  L. di Fabrizio  D. Fugazza  M. Giarrusso  E. Giro  F. Leone  V. Lorenzi  S. Scuderi 《Astronomische Nachrichten》2014,335(2):117-123

We describe a new polarimetric facility available at the Istituto Nazionale di AstroFisica / Telescopio Nazionale Galileo at La Palma, Canary islands. This facility, PAOLO (Polarimetric Add‐On for the LRS Optics), is located at a Nasmyth focus of an alt‐az telescope and requires a specific modeling in order to remove the time‐ and pointing position‐dependent instrumental polarization. We also describe the opto‐mechanical structure of the instrument and its calibration and present early examples of applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

The role of lower continental crust and lithospheric mantle in the genesis of Plio–Pleistocene volcanic rocks from Sardinia (Italy)     

Michele Lustrino  Leone Melluso  Vincenzo Morra 《Earth and Planetary Science Letters》2000,180(3-4):259-270

The first comprehensive chemical and Sr–Nd–Pb isotopic data set of Plio–Pleistocene tholeiitic and alkaline volcanic rocks cropping out in Sardinia (Italy) is presented here. These rocks are alkali basalts, hawaiites, basanites, tholeiitic basalts and basaltic andesites, and were divided into two groups with distinct isotopic compositions. The vast majority of lavas have relatively high ⁸⁷Sr/⁸⁶Sr (0.7043–0.7051), low ¹⁴³Nd/¹⁴⁴Nd (0.5124–0.5126), and are characterised by the least radiogenic Pb isotopic composition so far recorded in Italian (and European) Neogene-to-Recent mafic volcanic rocks (²⁰⁶Pb/²⁰⁴Pb=17.55–18.01) (unradiogenic Pb volcanic rocks, UPV); these rocks crop out in central and northern Sardinia. Lavas of more limited areal extent have chemical and Sr–Nd–Pb isotopic ratios indicative of a markedly different source (⁸⁷Sr/⁸⁶Sr=0.7031–0.7040; ¹⁴³Nd/¹⁴⁴Nd=0.5127–0.5129; ²⁰⁶Pb/²⁰⁴Pb=18.8–19.4) (radiogenic Pb volcanic rocks, RPV), and crop out only in the southern part of the island. The isotopic ratios of these latter rocks match the values found in the roughly coeval anorogenic (i.e. not related to recent subduction events in space and time) mafic volcanic rocks of Italy (i.e. Mt. Etna, Hyblean Mts., Pantelleria, Linosa), and Cenozoic European volcanic rocks. The mafic rocks of the two Sardinian rock groups also show distinct trace element contents and ratios (e.g. Ba/Nb>14, Ce/Pb=8–25 and Nb/U=29–38 for the UPV; Ba/Nb<9, Ce/Pb=24–28 and Nb/U=46–54 for the RPV). The sources of the UPV could have been stabilised in the Precambrian after low amounts of lower crustal input (about 3%), or later, during the Hercynian Orogeny, after input of Precambrian lower crust in the source region, whereas the sources of the RPV could be related to processes that occurred in the late Palaeozoic–early Mesozoic, possibly via recycling of proto-Tethys oceanic lithosphere by subduction.  相似文献   

Particulate matter and chemical-physical conditions of an inner sea: The Mar Piccolo in Taranto. A new statistical approach     

G. Alabiso  M. Cannalire  D. Ghionda  M. Milillo  G. Leone  O. Caciorgna 《Marine Chemistry》1997,58(3-4)

As part of the environmental recovery plan for the Mar Piccolo (Ionian Sea), a basin suffering especially from urban pollution, a study was planned on the modifications induced by the human activities to distinguish them from those due to the alternation of the seasons and the exchanges with the neighbouring basin of Mar Grande. The present paper deals with the chemical-physical characteristics of sea water and its particulate matter content is investigated as a part of this study. The physical, chemical and biological variables (stochastic variables for the model) are: chlorophyll a, proteins, carbohydrates, organic matter, dry weight, temperature, salinity, dissolved oxygen, pH, ultraviolet absorbance, phosphate, nitrite, nitrate, ammonia, silicate, photosynthetically available radiation (PAR) and energy. These variables have been sampled at 15 different stations during one year of monthly sampling. A preliminary analysis was carried out on the variables for detecting possible interactions among all the investigated parameters. To this purpose, and for all the variables, an original computer program for non-parametric statistical-evaluation and data-correlation was used to find correlation-guided hierarchy of variables. The relations among: Prot and Chl-a, Carb and Chl-a and OM and DW have been studied. The slopes of linear regression of (Prot, Chl-a) and (Carb, Chl-a) allowed us to detect different relations at different space-time areas. A nonlinear relation between OM and DW has been found as well. This treatment is a first approach to the construction of a mathematical model of the basin. Different areas, for sea water characteristics, were observed to occur in the basin, despite its small extension. This may be due to the reduced water exchanges and the different residential development along the coast. Innermost areas, less involved in the water mass circulation, were more affected by eutrophication.  相似文献   

<Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar ages of the<Emphasis Type="Italic"> AD</Emphasis> 79 eruption of Vesuvius,Italy     

Marvin Lanphere  Duane Champion  Leone Melluso  Vincenzo Morra  Annamaria Perrotta  Claudio Scarpati  Dario Tedesco  Andrew Calvert 《Bulletin of Volcanology》2007,69(3):259-263

The Italian volcano, Vesuvius, erupted explosively in AD 79. Sanidine from pumice collected at Casti Amanti in Pompeii and Villa Poppea in Oplontis yielded a weighted-mean ⁴⁰Ar/³⁹Ar age of 1925±66 years in 2004 (1σ uncertainty) from incremental-heating experiments of eight aliquants of sanidine. This is the calendar age of the eruption. Our results together with the work of Renne et al. (1997) and Renne and Min (1998) demonstrate the validity of the ⁴⁰Ar/³⁹Ar method to reconstruct the recent eruptive history of young, active volcanoes.  相似文献   

Correlation between strontium and oxygen isotopic compositions of rocks from the Adamello massif (Northern Italy)     

G. Cortecci  A. Del Moro  G. Leone  G. C. Pardini 《Contributions to Mineralogy and Petrology》1979,68(4):421-427

Rock samples from the lithologic units forming the Adamello massif were analyzed for Rb and Sr concentrations and for⁸⁷Sr/⁸⁶Sr and¹⁸O/¹⁶O ratios. The most important features are as follows:

1. the strontium and oxygen isotopes show a systematic variation from south to northwest across the massif, the older units in the south being lower both in⁸⁷Sr and¹⁸O;
2. a good positive correlation was found between strontium and oxygen isotopic compositions.

Two genetic models are advanced for explaining the results: (1) the mixing of two magmas with different¹⁸O and⁸⁷Sr contents; (2) magma formation at different depths in a crust layered with respect to both oxygen and strontium isotope composition.  相似文献   

Land cover and land use change in the Italian central Apennines: A comparison of assessment methods   总被引：1，自引：0，他引：1  

Raffaele Pelorosso  Antonio Leone  Lorenzo Boccia 《Applied geography (Sevenoaks, England)》2009,29(1):35-48

Analyses of land-use cover changes (LUCC) are fundamental to the understanding of numerous social, economical and environmental problems and can be carried out rapidly, using either cartographic or census data. However, the trends of the two methods differ in direction and quantity.For this study, a historical and a recent remote sensing-derived map were homogenized to reduce misleading changes and to assess spatial aggregation errors. This was carried out by means of a data integration procedure based on landscape metrics, allowing cartographic and census trends to be compared. Discrepancies between data were thus highlighted, both in absolute surface value and in evolution.The methodology presented, and the results obtained, could be employed to evaluate and improve LUCC analyses aimed at assessing landscape identity, both in the case of analyses based only on LU census data, or of those based only on LC cartographic data. This could lead to benefits for both biodiversity conservation and environmental planning on a large scale.  相似文献   

Volcanic history, geologic analysis and map of the Prometheus Patera region on Io     

Giovanni Leone  Ashley Gerard Davies  Lionel Wilson  David A. Williams  Laszlo P. Keszthelyi  Windy L. Jaeger  Elizabeth P. Turtle 《Journal of Volcanology and Geothermal Research》2009,187(1-2):93-105

Data from Jupiter's moon Io returned by the Galileo spacecraft have been used to create a geologic map of Prometheus Patera, its associated flow field, and nearby features. We have identified the location of the vent that fed the Prometheus flow field during the Galileo epoch in the north-eastern portion of the main Prometheus flow field. This vent is the probable source of a small sulphur-rich plume. Previous studies suggested that the vent may be atop a tectonic fault but we find that the vent is offset from the putative fault. It is plausible that, in the past, magma exploited the fault to reach the surface at Prometheus Patera, but subsequent magma cooling in the conduit could have caused an obstruction preventing further eruptions from providing significant contributions to the Prometheus flow field. We also speculate on how a new Prometheus plumbing system may be fed by mafic magmas after melt stalls in magma reservoirs during its ascent through the lithosphere from the mantle.  相似文献   

Auroral implications of recent measurements on O(1S) and O(1S) formation in the reaction of N+ with O2     

Andrew O. Langford  Veronica M. Bierbaum  Stephen R. Leone 《Planetary and Space Science》1985,33(10):1225-1228

Recent flowing afterglow measurements have shown that the reaction of N⁺ with O₂ produces 70 ± 30% of the oxygen atom product as $\text{O}\text{(}{}^1\text{D}\text{)}$ and < 0.1% as $\text{O}\text{(}{}^1\text{S}\text{)}$. These results indicate that this reaction does not contribute to the auroral green line emission (5577 Å), but can account for ～10% of the observed red line (6300 Å) auroral emission.  相似文献